Payout coil impregnated with conductive adhesive

ABSTRACT

A wire-guided torpedo payout coil including a container which has an exit opening; a coil of insulated wire disposed within the container with a portion of the wire extending through the exit opening; and the voids within the coil of wire being filled with a conductive adhesive, such as an adhesive mixture of silicone fluid and graphite, such as carbon black.

United States Patent Richard W. de Nobel Silver Spring;

Donald G. Schurman, Rockville; Theodore J. Lindstadt, Jr., Oleny; HansA. Koenig, Rockville, all of Md.

Dec. 5, 1969 Oct. 19, 1971 The United States of America as representedby the Secretary of the Navy Inventors Appl. No. Filed Patented AssigneePAYOUT COIL IMPREGNATED WITH CONDUCTIVE ADHESIVE 7 Claims, 2 DrawingFigs.

US. Cl 114/21, 244/312 Int. Cl F42b 19/06 i 1 7e- 1 I} l A /777 [50]Field ofSearch 114/21; 174/235; 244/312 [56] References Cited UNITEDSTATES PATENTS 3,156,185 11/1964 Hermann et a1. 244/3.l2 3,319,7815/1967 Simpson et al.... 244/3. 1 2 3,395,669 8/1968 Keenan 1 14/238Primary Examiner-Samuel einberg Assistant Examiner-Har0ld .1. TudorAttorneys-Richard S. Sciascia and Ervin F. Johnston ABSTRACT: Awire-guided torpedo payout coil including a container which has an exitopening; a coil of insulated wire disposed within the container with aportion of the wire extending through the exit opening; and the voidswithin the coil of wire being filled with a conductive adhesive, such asan adhesive mixture of silicone fluid and graphite, such as carbonblack.

' PATENTEUBBI 19 ran I III PAYOUT COIL IMPREGNATED WITH CONDUCTIVEADHESIVE In the wire-guided torpedo concept control signals aretelemetered from a mother vehicle over a very fine insulated wire to atorpedo. Since it is anticipated that both the vehicle and the torpedoare moving in the water the wire is disposed in a coil at bothlocations. Accordingly, as either or both the vehicle or torpedo move inthe water the wire is freely payed out and lays substantially motionlessin the water so that there is practically no strain thereon.

At the torpedo location the payout coil is disposed within a containerwhich has an exit opening. in many applications a long slender tubeabout one-fourth inch in diameter extends aft in the torpedo from theexit opening of the container, and wire from the payout coil extendstherethrough to the mother vehicle. Normally the container and the coilof wire disposed therein are submerged in a salt water environment andsea water will nonuniformly penetrate the voids within the coil of wire.It can readily be visualized that when the torpedo is being controlledat a speed of about 30 knots the wire isuncoiling quite rapidly andthereafter spins within the sea water in the container until it travelsthrough the slender tube. In

- order to prevent multiple turns of the wire from uncoilingsimultaneously from the coil during payout the prior art teaches the useof a rubber base adhesive which binds the individual turns of wire ofthe coil. This adhesive is applied in a wet state to the wire as thecoil is being wound and it only partially fills the void space betweenthe turns of wire. As a result sea water penetrated the voids within thecoil nonuniformly and the payout-restraining force of the coil wassomewhat nonuniform.

As a result of this variation of sea water penetration into the coil, ithas been very difficult to predict the electrical characteristics of thecoil during payout. The shunt capacity of the coil varies during payoutsince the sea water nonuniformly penetrates the voids left in the coilby the rubber base adhesive. It would be highly desirable if the veryfine filament wire of the coil would behave like a coaxial conductorwith the outer conductor conductive enough to provide a shunt capacityfor the coil which is substantially fixed over the frequency band whichis used for communication between the mother vehicle and the torpedo. Asa means to provide this advantage we have tried a wire with a very thincopper sheath. However, this process is quite expensive.

As mentioned hereinabove one of the disadvantages of utilizing a rubberbase adhesive for the coil of wire is that the restraining force isnonuniform during payout. This is due again to the partial filling ofthe rubber base adhesive within the voids of the coil of wire. Stillanother serious disadvantage of using the rubber base adhesive is thatwhen torpedoes are operated at speeds greater than 30 knots the adhesiveoften collects in a large mass in the payout tube of the coil containerand imposes an undesirable restraining force on the very fine filamentwire as it is payed out through the tube. At speeds of 40 knots andabove this force has been sufficient to break the wire and ceasecommunication between the mother vehicle and the torpedo. Yet anotherproblem with the rubber base adhesive is the low ratio of tack force topeel force on the individual turns as they are payed out from the coil.A high tack force is desirable to that adjacent turns will not uncoilsimultaneously. A low peel force is desirable so that little forceisrequired to peel the individual turns from the coil. With the rubberbase adhesive the peel force has been too high and when speeds of 40knots or greater are involved breakage of the wire is quite probable.

We have overcome the aforementioned problems associated with the use ofrubber base adhesives by impregnating the payout coil with a conductivegreaselike material. Specifically, we have discovered that a mixture ofsilicone fluid and carbon black has worked quite satisfactorily inovercoming the aforementioned problems. With a proper mixture ofsilicone fluid and carbon black all voids within the payout coil arefilled and the ratio of tack force to peeling force on the individualturns is kept quite high as they pay out. The

peeling force is significantly less than that which is characteristic tothe rubberbase adhesive. The conductive particles within the mixtureestablish the turn-to-tum capacitance of the coil and provides shuntcapacitance over the entire length of the wire within the coil so thatthe capacitance effect of the coil is substantially uniform duringpayout. We have found that acetylene carbon black is especiallydesirable in the mix ture for this purpose. No mechanical difficultieshave been experienced with the mixture since the fluid mixture imposesno restraining force on'the wire as it is payed out through the slendertube.

An object of the present invention is to overcome the aforementionedproblems associated with'prior art torpedo payout coils.

Another object is to provide a torpedo payout coil which imposessubstantially no electrical and/or mechanical problems to communicationbetween a mother vehicle and the torpedo even though the torpedo iscontrolled at speeds greater than 40 knots.

Still another object is to provide an adhesive-impregnated torpedopayout coil wherein the adhesive completely fills the voids within thecoil and minimizes undesirable capacitance.

effects of the coil to communications between the mother vehicle and thetorpedo.

A further object is to provide an adhesive-impregnated tor-. pedo payoutcoil wherein the adhesive provides desirable electn'cal conditions anddoes not impose undue restraining force on the wire as it is payed outfrom the torpedo.

Still a further object is to provideadhesive-impregnated coils ofinsulated wire which have predictable electrical characteristics.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as it becomes better understood by referenceto the description and accompanying drawings which follow.

FIG. 1 is an ocean view of a mother vehicle controlling a wire-guidedtorpedo.

FIG. 2 is a side view partially in cross section of a torpedo coilpayout apparatus.

Referring now to the drawing there is shown in FIG. 1 a torpedo 4 whichis guided by a very fine insulated wire 6 from a mother vehicle, such asa submarine 8. In the after portion of the torpedo is a wire payoutapparatus which is illustrated generally at 10 in FlG. 2. This payoutapparatus 10 may include a container 12 and a coil 14 of the very fineinsulated wire 6 disposed therein. The coil 14 illustrated is an insidepayout-type coil, however, it could, if desired, be the outside payouttype of coil. The aft end of the container 12 may neck down to an exitopening 16 where there is mounted a slender tube 18 which also extendsin the aft direction. A portion of the wire 6 from the coil 14 extendsthrough the tube 18 and thence to the submarine 8 which telemeterssignals via the wire for controlling the torpedo. The payout apparatus10 is mounted in the aft portion of the torpedo and the interior of thecontainer 12 is normally flooded with sea water. The submarine may havea similar payout apparatus as the payout apparatus 10 shown in FIG. I.

All voids within the coil 14 are filled with a conductive binder whichis a mixture of fluid and conductive particles. We have found that amixture of silicone fluid and carbon, such as carbon black, works quitesatisfactorily for our intended purposes. The best results were achievedwhen the carbon black was acetylene carbon black. Acetylene carbon blackhas long slender molecules which easily contact one another within thesilicone fluid so that a desired mixture can be prepared which easilyfills all of the voids within the coil 14 and provides good shuntcapacitance between all portions of the wire within the coil. A mixtureof silicone fluid and acetylene carbon black can be easily prepared withthe following desirable parameters: (1) a viscosity of 300 poises at atemperature of 77? F. and at a shear rate of 50 reciprocal seconds asdetermined by Federal Test Method Standard No. 791, Method 306.4; (2) aworked penetration of 250 to 290 at 77 F. as determined by Federal TestStandard No. 791, Method 31 1.6; and (3) a DC resistance of 20ohm-centimeters at 77 F. when the resistance of a sample of the mixtureis tested in a DC bridge or its equivalent. We have found a mixture ofsilicone fluid and acetylene carbon black in the following ratio to meetthe aforementioned parameters:

7 parts by weight silicone fluid such as GE SF96(I00) (100 centistokesviscosity); and

1 part by weight acetylene carbon black such as Shawinigan acetyleneblack 100 percent compression). The ingredients must be thoroughlycombined so that the mixture is homogeneous.

In the preparation of the payout coil 14 the wire is wound on anordinary spooling machine and mixture of silicone fluid and acetylenecarbon black is extruded onto the wire just prior to the spoolingoperation. The process would be the same whether the coil of wire is ofthe inside or outside payout type. Because of the desirablecharacteristics of the mixture all voids within the coil 14 will befilled with the conductive adhesive mixture and impregnation will becomplete.

In the operation of the coil apparatus 10 wire 6 is uncoiled from thecoil 14 and travels through the tube 18 as the torpedo moves through thewater in response to telemetered commands from the submarine. Because ofthe complete impregnation of the coil 14 the inductance and capacitancecharacteristics of the coil are predictable and impose substantially nointerference on communications between the mother ship and the torpedo.The complete penetration of the conductive adhesive also results in auniform restraining force as the wire is payed out through the tube 18.At speeds of the torpedo greater than 40 knots the mixture of conductiveadhesive has imposed no appreciable restraining force on the wire 6 asit travels through the slender tube 18. Apparently, the mixture ofconductive adhesive readily mixes with the water during payout and hasno tendency to collect in mass form at the entrance of or along the tube18.

The present invention is useful in combination with any coil of wirewhich is used for communication purposes whether the coil is in or outof the water or in or out of a container. A coil of wire impregnatedwith the aforementioned mixture can be easily tested out of water andits electrical integrity can be thus ascertained.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims that theinvention may be practiced otherwise than as specifically described.

We claim:

I. In a wire-guided torpedo payout coil apparatus:

a container which has an exit opening;

a coil of insulated wire disposed within the container with a portion ofthe wire extending through said exit opening; and

-the voids within the coil of wire being filled with a conductiveadhesive.

2. The combination as claimed in claim I wherein:

a slender tube is mounted to the container and extends from said exitopening; and

a portion of the wire extending through said slender tube.

3. The combination as claimed in claim 2 wherein:

the conductive adhesive is a mixture of silicone fluid and carbon.

4. The combination as claimed in claim 3 wherein:

the carbon is carbon black.

5. The combination as claimed in claim 4 wherein:

the carbon black is acetylene carbon black.

6. The combination as claimed in claim 5 wherein the parameters of themixture of conductive adhesive are substantially as follows:

a viscosity of 300 poises at a temperature of 77 F. and at a shear rateof 50 reciprocal seconds;

a worked penetration of 25o 290 at 77 F.;

DC resistance of 20 ohm-centimeters at 77 F.

acetylene carbon black is approximately I part by weight.

1. In a wire-guided torpedo payout coil apparatus: a container which has an exit opening; a coil of insulated wire disposed within the container with a portion of the wire extending through said exit opening; and the voids within the coil of wire being filled with a conductive adhesive.
 2. The combination as claimed in claim 1 wherein: a slender tube is mounted to the container and extends from said exit opening; and a portion of the wire extending through said slender tube.
 3. The combination as claimed in claim 2 wherein: the conductive adhesive is a mixture of silicone fluid and carbon.
 4. The combination as claimed in claim 3 wherein: the carbon is carbon black.
 5. The combination as claimed in claim 4 wherein: the carbon black is acetylene carbon black.
 6. The combination as claimed in claim 5 wherein the parameters of the mixture of conductive adhesive are substantially as follows: a viscosity of 300 poises at a temperature of 77* F. and at a shear rate of 50 reciprocal seconds; a worked penetration of 250-290 at 77* F.; DC resistance of 20 ohm-centimeters at 77* F.
 7. The combination as claimed in claim 6 wherein: the silicone fluid is approximately 7 parts by weight and the acetylene carbon black is approximately 1 part by weight. 